Re: [PATCH RESEND v6 4/9] pmem,mm: Implement ->memory_failure in pmem driver
From: Dan Williams <hidden>
Date: 2021-08-20 20:51:37
Also in:
dm-devel, linux-fsdevel, linux-mm, linux-xfs, lkml
On Fri, Jul 30, 2021 at 3:02 AM Shiyang Ruan [off-list ref] wrote:
With dax_holder notify support, we are able to notify the memory failure from pmem driver to upper layers. If there is something not support in the notify routine, memory_failure will fall back to the generic hanlder.
How about: "Any layer can return -EOPNOTSUPP to force memory_failure() to fall back to its generic implementation."
quoted hunk ↗ jump to hunk
Signed-off-by: Shiyang Ruan <redacted> --- drivers/nvdimm/pmem.c | 13 +++++++++++++ mm/memory-failure.c | 14 ++++++++++++++ 2 files changed, 27 insertions(+)diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 1e0615b8565e..fea4ffc333b8 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c@@ -362,9 +362,22 @@ static void pmem_release_disk(void *__pmem) del_gendisk(pmem->disk); } +static int pmem_pagemap_memory_failure(struct dev_pagemap *pgmap, + unsigned long pfn, unsigned long nr_pfns, int flags) +{ + struct pmem_device *pmem = + container_of(pgmap, struct pmem_device, pgmap); + loff_t offset = PFN_PHYS(pfn) - pmem->phys_addr - pmem->data_offset; + + return dax_holder_notify_failure(pmem->dax_dev, offset, + page_size(pfn_to_page(pfn)) * nr_pfns,
I do not understand the usage of page_size() here? memory_failure()
assumes PAGE_SIZE pages. DAX pages also do not populate the compound
metadata yet, but even if they did I would expect memory_failure() to
be responsible for doing something like:
pgmap->ops->memory_failure(pgmap, pfn, size >> PAGE_SHIFT, flags);
...where @size is calculated from dev_pagemap_mapping_shift().
+ &flags);
Why is the local flags variable passed by reference? At a minimum the memory_failure() flags should be translated to a new set dax-notify flags, because memory_failure() will not be the only user of this notification interface. See NVDIMM_REVALIDATE_POISON, and the discussion Dave and I had about using this notification to signal unsafe hot-removal of a memory device.
quoted hunk ↗ jump to hunk
+} + static const struct dev_pagemap_ops fsdax_pagemap_ops = { .kill = pmem_pagemap_kill, .cleanup = pmem_pagemap_cleanup, + .memory_failure = pmem_pagemap_memory_failure, }; static int pmem_attach_disk(struct device *dev,diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 3bdfcb45f66e..ab3eda335acd 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c@@ -1600,6 +1600,20 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags, */ SetPageHWPoison(page); + /* + * Call driver's implementation to handle the memory failure, otherwise + * fall back to generic handler. + */ + if (pgmap->ops->memory_failure) { + rc = pgmap->ops->memory_failure(pgmap, pfn, 1, flags); + /* + * Fall back to generic handler too if operation is not + * supported inside the driver/device/filesystem. + */ + if (rc != EOPNOTSUPP) + goto out; + } + mf_generic_kill_procs(pfn, flags); out: /* drop pgmap ref acquired in caller */ --2.32.0